I’m a PhD candidate and associate lecturer, originally from Wolverhampton.
I never really developed a thick Black Country accent. Whenever I speak to people at conferences and I tell them where I’m from, there’s always a somewhat congratulatory “oh, you can’t tell!” reaction.
I seem to be in a minority of English people, with my nonstandard Leicester accent, who pronounce “tongue” “tong” rather than “tung”. It got mocked at university, and even my wife finds it so funny that I’ve actually altered the way I say it, or avoid saying the word aloud. It’s a small thing, sure, but it does make me very self conscious.